In wireless telecommunication networks, Long-Term Evolution, or “LTE,” is defined as a standard for wireless communication of high-speed data for mobile phones and data terminals. The LTE standard is developed by the Third Generation Partnership Project (“3GPP”) and the Institute of Electrical and Electronics Engineers (“IEEE”). An exemplary LTE access network is a wireless network of base stations, or evolved NodeBs (“eNBs”), that are interconnected without a centralized intelligent controller.
Long-term evolution (“LTE”) is a wireless communication standard used for high-speed data for mobile devices and data terminals. LTE-Advanced is a major enhancement to the LTE standard. Within the LTE-Advanced standard, carrier aggregation is used to increase the bandwidth, and thereby increase the bitrates. Carrier aggregation has been introduced in the 3rd Generation Partnership Project (“3GPP”) Release 10 (LTE-Advanced standard) to provide wider than 20 MHz transmission bandwidth to a single device (e.g., user equipment or “UE”) while maintaining the backward compatibility with legacy UEs. Specifically, carrier aggregation may be defined as the aggregation of two or more component carriers in order to support wider transmission bandwidths. Carrier aggregation configuration may be defined as a combination of carrier aggregation operating bands, each supporting a carrier aggregation bandwidth class by a UE. The bandwidth class may be defined by the aggregated transmission bandwidth configuration and maximum number of component carriers supported by a UE.
For intra-band contiguous carrier aggregation, a carrier configuration may be a single operating band supporting a carrier aggregation bandwidth class. For each carrier aggregation configuration, requirements may be specified for all bandwidth combinations contained within a bandwidth combination set, as indicated by the radio access capabilities of the UE. Accordingly, a UE may indicate support of several bandwidth combination sets for each band combination.
Under the current standards, each aggregated carrier is referred to as a component carrier, and each component carrier can have a bandwidth of 1.4, 3, 5, 10, 15 or 20 MHz and a maximum of five component carriers can be aggregated. As illustrated in FIG. 1, two exemplary component carriers may each have a bandwidth of 10 MHz to combine for a total bandwidth of 20 MHz. With carrier aggregation (“CA”) features enabled, the LTE-Advanced standard device supporting 20 MHz carrier aggregation may achieve downlink throughput of 100 Mbps.
In the frequency division duplex (“FDD”) CA case, the number of aggregated carriers can be different in the downlink (“DL”) and the uplink (“UL”). However, the number of UL component carriers is always equal to or lower than the number of DL component carriers. The individual component carriers can also be of different bandwidths. For time division duplex (“TDD”) CA case, the number of component carriers, as well as the bandwidths of each component carrier, will normally be the same for DL and UL.